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Scratch (programming language)
Scratch (programming language)
Scratch (programming language)
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This article is about the programming language. For other uses, see Scratch (disambiguation).

Scratch
Scratch logo
Logo used since 16 October 2015
Scratch 3.0 editor
ParadigmEvent-driven, block-based programming language
DeveloperScratch Foundation
First appeared
  • 11 October 2003; 22 years ago (2003-10-11) (prototype Scratch 0.1)[1]
  • 15 May 2007; 18 years ago (2007-05-15) (Scratch 1.0)[2]
  • 9 May 2013; 12 years ago (2013-05-09) (Scratch 2.0)
  • 2 January 2019; 6 years ago (2019-01-02) (Scratch 3.0)
Stable release
  • Scratch 3.0 (online editor) / 2 January 2019; 6 years ago (2019-01-02)
  • Scratch 3.29.1 (offline editor) / 27 February 2022; 3 years ago (2022-02-27)
Implementation languageSqueak (Scratch 1.x)
ActionScript (Scratch 2.0)[3]
HTML5, JavaScript (Scratch 3.0)[3][4]
OSMicrosoft Windows, macOS, Linux (via renderer), HTML5 (via web browser), iOS, iPadOS, and Android.
License

GNU Affero General Public License (Scratch 3.0)[5]

Filename extensions.sb, .sprite (Scratch 1.x)
.sb2, .sprite2 (Scratch 2.0)
.sb3, .sprite3 (Scratch 3.0)
Websitescratch.mit.edu
Influenced by
Logo, Smalltalk, HyperCard, StarLogo, AgentSheets, AgentCubes, Etoys, Snap!
Influenced
Catrobat,[6] ScratchJr,[7] Snap!,[8] mBlock, Turtlestitch

Scratch is a high-level, block-based visual programming language and website aimed primarily at children as an educational tool, with a target audience of ages 8 to 16.[9][10] Users can create projects on the website using a block-like interface. Scratch was conceived and designed through collaborative National Science Foundation grants awarded to Mitchel Resnick and Yasmin Kafai.[11]

Scratch is developed by the MIT Media Lab and has been translated into 70+ languages, being used in most parts of the world. Scratch is taught and used in after-school centers, schools, and colleges, as well as other public knowledge institutions. As of 15 February 2023, community statistics on the language's official website show more than 123 million projects shared by over 103 million users, and more than 95 million monthly website visits.[12] Overall, more than 1.15 billion projects have been created in total, with the site reaching its one billionth project on April 12th, 2024.[citation needed]

Scratch takes its name from a technique used by disk jockeys called "scratching", where vinyl records are clipped together and manipulated on a turntable to produce different sound effects and music. Like scratching, the website lets users mix together different media (including graphics, sound, and other programs) in creative ways by creating and "remixing" projects, like video games, animations, music, and simulations.[13]

Scratch 3.0

[edit]

User interface

[edit]
A program to change the background and make a sprite speak

The Scratch interface is divided into three main sections: a stage area, block palette, and a coding area to place and arrange the blocks into scripts that can be run by pressing the green flag or clicking on the code itself. Users may also create their own code blocks, which will appear in the "My Blocks" section.

The stage area features the results (e.g., animations, turtle graphics, either in a small or normal size, with a full-screen option also available) and all sprites' thumbnails being listed in the bottom area. The stage uses x and y coordinates, with 0,0 being the stage center.[14]

With a sprite selected at the bottom of the staging area, blocks of code can be applied by dragging them from the block palette into the coding area. The Costumes tab allows users to change the look of the sprite with a vector and bitmap editor in order to create various effects, including animation.[14] The Sounds tab allows attaching sounds and music to a sprite.[15]

When creating sprites and also backgrounds, users can draw their own sprites manually,[14] choose a sprite from the library, or upload an image.[15]

The table below shows the categories of the programming blocks:

Block categories in Scratch
Category Notes
Motion Movements of sprites, like angles and directions.
Looks Controls the visuals of the sprite.
Sound Plays audio files and effects.
Events Event handlers and broadcasters.
Control Conditionals, loops, and cloning.
Sensing Interactions between sprites, the mouse pointer, and the backdrop.
Operators Mathematical operators, conjunctions, and comparisons.
Variables Blocks to access and set variables. Cloud variables are synced across all running versions of the project.
Lists Blocks to access and interact with lists.
My Blocks User-defined functions, accessible as blocks. They can have inputs and have the option to run without a screen refresh.
Extensions Extra categories (e.g. Pen, Music) of blocks that can be added to a project at any time.

Offline editing

[edit]
One of the 4 different scripts for the getting started built-in tutorial.
Four different scripts for the getting started built-in tutorial
A coded example, using the ask block for the users' name, then responding with it,
A coded example, using the ask block for the users' name, then responding with it

An offline "Desktop Editor" for Scratch 3.0 is available for Microsoft Windows 10 and above in the Microsoft Store, Apple's macOS, ChromeOS, Android, and unofficially in Linux here; (although Scratch states on their download page that they are working with open-source partners to support Linux in the future)[16] this allows the creation and playing of Scratch programs offline. The offline editor can also be downloaded in previous versions, such as Scratch 2.0 and Scratch 1.4 (an archive of older versions is found here).

Extensions

[edit]

In Scratch, extensions add extra blocks and features that can be used in projects. In Scratch 2.0, the extensions were all hardware-based and Pen was a normal category. Software-based extensions were added in Scratch 3.0, such as text-to-speech voices, along with some new hardware-based extensions like the micro:bit. The extensions are listed below.

An example of the Scratch 3 Extensions Page

Physical

[edit]
  • LEGO Mindstorms EV3 – Control motors and receive sensor data from the Lego Mindstorms EV3
  • Makey Makey – Use Makey Makey to control projects
  • LEGO Education WeDo 2.0 – control motors and receive sensor data from the Lego WeDo
  • micro:bit – Use of a micro:bit to control projects
  • LEGO BOOST – Bring robotic creations to life
  • Go Direct Force & Acceleration – Sense pull, push, motion, and spin

Digital

[edit]

Many of the digital extensions in Scratch 3.0 used to be regular block categories that were moved to the extensions section to reduce clutter. These include:

  • Music – Play digital instruments (drums, trumpets, violins, pianos, and more). Previously part of the Sound category.
  • Pen – Draw on the Stage with a variety of thicknesses and color. Previously a normal block category.
  • Video Sensing – Detect motion with the camera. Previously in the Sensing category.

New digital extensions have also been added in collaborations with commercial companies. These include:

  • Text to Speech – Converts words in a text into voice output, especially having an option for languages (variety of voices, supplied by Amazon)
  • Translate – Uses Google Translate to translate text from one language into a variety of other languages, including Arabic, Chinese, Dutch, English, French, Greek, Norwegian, and Japanese
  • Makey Makey – Options for better key pressing and press multiple keys in order. You can grab a join block if you want more control on the extension.

A paper published in 2019 by NYU argues and illustrates, for coding music with Scratch, "that the music and sound blocks as currently implemented in Scratch may limit and frustrate meaningful music-making for children, the core user base for Scratch."[17]

Scratch Lab

[edit]

The Scratch Lab[18] displays experiments from the Scratch Team, intended to explore whether new features may be added to the full website in the future. Experimental features currently under development include:

  • Video Sprites – Fill sprites with live video.
  • Face Sensing – Make animated costumes and games that interact with a user's face.
  • Animated Text – Bring words to life with colors, fonts, and animations.

Community of users

[edit]
A Scratch programming workshop

Scratch is used in many different settings: schools, museums, libraries, community centers, and homes.[19][20][21] Scratch is designed primarily for users aged 8–16, but it is used by all ages and has a sizeable adult user base as of 2009.[10][22] This wide outreach has created many surrounding communities, both physical and digital.[12] In April 2020, the Tiobe ranking of the world's programming languages included Scratch in the top 20. According to Tiobe, there are 50 million projects written in Scratch, and every month one million new projects are added.[23]

Educational users

[edit]

Scratch is used as the introductory language because the creation of interesting programs is relatively easy, and skills learned can be applied to other programming languages such as Python and Java.

Scratch is not exclusively for creating games. With the provided visuals, programmers can create animations, text, stories, music, art, and more. There are already many programs that students can use to learn topics in math, history, and even photography. Scratch allows teachers to create conceptual and visual lessons and science lab assignments with animations that help visualize difficult concepts. Within the social sciences, instructors can create quizzes, games, and tutorials with interactive elements. Using Scratch allows young people to understand the logic of programming and how to creatively build and collaborate.[24]

Scratch is taught to more than 800 schools and 70 colleges of the DAV organization in India and across the world.[25][26]

In higher education, Scratch is used in the first week of Harvard University's CS50 introductory computer science course.[27][28]

Online community

[edit]
An example of a game created with Scratch 2.0

Users of Scratch are called "Scratchers". Scratchers have the capability to share their projects and receive feedback. Projects can be uploaded directly from the development environment to the Scratch website and any member of the community can view and download the full source code to study or to remix into new projects.[29][30] Scratchers can also create project studios, comment, favorite, and "love" others' projects, follow other members to see their projects and activity, and share ideas. Projects range from games and animations to practical tools. Additionally, to encourage the creation and sharing amongst users, the website frequently establishes "Scratch Design Studio" challenges.[31]

Educators have their own online community called ScratchEd, developed and supported by the Harvard Graduate School of Education. In this community, Scratch educators share stories, exchange resources, and ask questions.[32][non-primary source needed]

Scratch Studios

[edit]

Scratchers can upload their projects to studios where other Scratchers can upload their project for others to see and for other Scratchers to view, comment and remix their project. A studio usually consists of different projects made by Scratchers. Some Scratch studios are created by Scratchers to put all their projects into one library.

Shadow on Scratch
An example of a game created with Scratch 3.0

Scratch Wiki

[edit]

The Scratch Wiki is a support resource for Scratch and information about its website, history, and phenomena surrounding it. Although supported by the Scratch Team (the developers of Scratch), it is primarily written by Scratch users (Scratchers) and is hosted independently of the main Scratch website.[33]

Roles

[edit]

Roles are displayed as a label under a user's username on profile pages and on forum posts. To prevent vandalism, new accounts have the "New Scratcher" role, as opposed to the usual "Scratcher" role. Some restrictions are imposed onto New Scratcher accounts, including the inability to use cloud data and a minimum 30 second cooldown period between posting comments.[34][user-generated source] After a period of time of interacting and creating projects, an account will be eligible to gain the Scratcher role.[35]

Official moderators and developers of Scratch are labeled as part of the "Scratch Team" and usually have an asterisk at the end of their username.[36] The site also has special types of accounts for Students and Educators to use Scratch in the classroom.[37]

Censorship

[edit]

In August 2020, GreatFire announced that the Chinese government had blocked access to the Scratch website. At the time, it was estimated that more than three million people in China were using it.[38][citation needed] The outlet cited the fact that Macau, Hong Kong and Taiwan were listed as countries on the website.[38][39]

Code base

[edit]

The source code for the project editor in all three major versions, as well as a majority of the current website, is hosted publicly on GitHub across various repositories.[40] Scratch 3.0 is JavaScript-based, 2.0 is programmed in ActionScript,[4] and the 1.x versions were based on Squeak, which itself is based on Smalltalk-80.[41]

2.0 had an experimental JavaScript-based interpreter that was being developed in parallel with the ActionScript version.[42]

On 13 May 2014, a year after the release of Scratch 2.0, it was announced by a developer on the Scratch Forums that 2.0 would become open source.[43]

In 3.0, Scratch blocks are implemented using Blockly, a JavaScript library developed by Google for creating block-based visual programming languages.[44][45]

Events

[edit]

Scratch Educators can gather in person at Scratch Educator Meetups. At these gatherings, Scratch Educators learn from each other and share ideas and strategies that support computational creativity.[46]

An annual "Scratch Week", formerly known as "Scratch Day", is declared in May each year. Community members are encouraged to host an event on or around this day, large or small, that celebrates Scratch. These events are held worldwide, and a listing can be found on the Scratch Day website. Scratch Week is a series focusing on Scratch activities on the Scratch website.[47]

Every April Fools' Day, the Scratch Team will play pranks on users and add Easter eggs, one example being that all event blocks in projects turn into cat versions of the same blocks.

History

[edit]

In the early 2000s, the MIT Media Lab's Lifelong Kindergarten group (LLK) was developing visual programming languages targeted towards children.[48] In 2003, Mitchel Resnick, Yasmin Kafai, and John Maeda were awarded a National Science Foundation grant for the development of a new programming environment for children to express themselves with code.[11] The LLK, led by Mitchel Resnick, in partnership with Yasmin Kafai's team at UCLA worked closely with Computer Clubhouses in Boston and Los Angeles to develop Scratch, grounding its design in the practices and social dynamics of these after-school youth centers.[11] It started as a basic programming language, with no labeled categories and no green flag.[49] Similar to AgentSheets[50] Scratch employed concepts of Tactile Programming later known as blocks-based programming. Scratch was made with the intention to teach kids to program.[49]

The philosophy of Scratch encourages the sharing, reuse, and combination of code, as indicated by the team slogan, "Imagine, Program, Share".[51] Users can make their own projects, or they may choose to "remix" someone else's project. Projects created and remixed with Scratch are licensed under the Creative Commons Attribution-ShareAlike License.[52] Scratch automatically gives credit to the user who created the original project and program in the top part of the project page.[21]

Scratch was developed based on ongoing interaction with youth and staff at Computer Clubhouses. The use of Scratch at Computer Clubhouses served as a model for other after-school centers demonstrating how informal learning settings can support the development of technological fluency.[53]

Scratch 2.0 was released on 9 May 2013.[14] The update changed the look of the site and included both an online project editor and an offline editor.[54] Custom blocks could now be defined within projects, along with several other improvements.[55] The Scratch 2.0 Offline editor could be downloaded for Windows, Mac, and Linux directly from Scratch's website, although support for Linux was later dropped. The unofficial mobile version had to be downloaded from the Scratch forums.[56][57]

The Scratch website's homepage

Scratch 3.0 was first announced by the Scratch Team in 2016. Several public alpha versions were released between then and January 2018, after which the pre-beta "Preview" versions were released.[58] A beta version of Scratch 3.0 was released on 1 August 2018.[59] for use on most browsers; with the notable exception of Internet Explorer.[60]

Scratch 3.0, the first 3.x release version, was released on 2 January 2019.[61] On 28 June 2023,[62] the header and links on the Scratch Website changed from blue to purple, and new optional high-contrast block colors were introduced, to make the site easier for colorblind people to read and use.[63]

In 2013, the Scratch Foundation (formerly the Code-To-Learn Foundation) was founded, and on March 11, 2019, the Scratch Team separated from the MIT Media Lab and moved to the Scratch Foundation.[64] The MIT Media Lab continues to collaborate closely with the Scratch Foundation.

Scratch Foundation

[edit]

The Scratch Foundation (formerly the Code to Learn Foundation) is a company founded in 2013 to hold the ownership of Scratch and ScratchJr. The MIT Media Lab transferred Scratch and ScratchJr to the Scratch Foundation in 2019. Their website can be found here.

Filetypes

[edit]

In Scratch 1.4, an *.sb file was the file format used to store projects.[65]

An *.sb file is divided into four sections:

  • "header", this 10-byte header contains the ASCII string "ScratchV02" in versions higher than Scratch 1.2, and "ScratchV01" in Scratch 1.2 and below
  • "infoSize", encodes the length of the project's infoObjects. A 4-byte long, 32-bit, big-Endian integer.
  • "infoObjects", a dictionary-format data section. It contains: "thumbnail", a thumbnail of the project's stage; "author", the username of the project's creator; "comment", the Project Notes; "history", the save and upload log; "scratch-version", the version of Scratch used to save the file;
  • "contents", an object table with the Stage as the root.[66] All objects in the program are stored here as references.[67]

Scratch 2.0 uses the *.sb2 file format. These are essentially zip files containing a .json file as well as the contents of the Scratch project including sounds (stored as .wav) and images (stored as .png).[68] Each filetype, excluding the project.json, is stored as a number, starting at 0 and counting up with each additional file. The image file labeled "0.png" is always a 480x360 white image, but "0.wav" will still be the earliest non-deleted file.

The ScratchX experimental version of Scratch used the .sbx file format.[69]

Scratch 3.0 uses the *.sb3 format.[70]

Older versions

[edit]

Although the main Scratch website now runs only the current version (Scratch 3.0), the offline editors for Scratch 2.0 (and the earlier Scratch 1.4) are still available for download[71] and can be used to create and run games locally.[72] It is still possible to upload projects from the Scratch 2.0 launcher, which are immediately converted into Scratch 3.0 when uploaded to the main site.[73] There is also an offline version of Scratch 3.0.

Technology

[edit]

The editor of Scratch 1.4 and below was written in Squeak, while its online project viewer was written in Java, and a player written in Adobe Flash was later added.[41][74] Scratch 2.0 relied on Adobe Flash for the online version, and Adobe AIR for the offline editor. These have fallen out of favor, and Adobe dropped support for them at the end of 2020.[75][76]

Scratch 2.0 changed how sounds were imported, so many Scratch 1.4 sounds stopped working. (The project file was changed from *.sb to *.sb2).[77]

Interface

[edit]
A script that lets the sprite say Hello, World! then stops the script in Scratch 2.0.

In Scratch 2.0, the stage area is on the left side, with the programming blocks palette in the middle, and the coding area on the right. Extensions are in the "More Blocks" section of the palette.[22]

The web version of Scratch 2.0 introduced project autosaving.[78]: 23 

The blocks palette in Scratch 2.0 is made of discrete sections that are not scrollable from one to the next; the table below shows the different sections:

Interface sections in Scratch
Category Notes
Motion Moves and changes the position of sprites
Events Event handlers
Looks Controls the visuals of the sprite
Control Conditionals and loops
Sound Audio files, sequences, and music
Sensing Sprite interaction
Pen Draw on the canvas
Operators Mathematical operators
Data Variables, arrays and lists
More Blocks Functions and extensions, return value is always void

Scratch 2.0 introduced the backpack, which can be used to transfer scripts, sprites, costumes, and sounds between projects.[78]: 14–15 

Features

[edit]

Scratch uses event-driven programming with multiple active objects called sprites.[14] Sprites can be drawn, as vector or bitmap graphics, from scratch in a simple editor that is part of Scratch, or can be imported from external sources. Scratch 3.0 only supports one-dimensional arrays, known as "lists", and floating-point scalars and strings are supported but with limited string manipulation ability. There is a strong contrast between the powerful multimedia functions and multi-threaded programming style and the rather limited scope of the Scratch programming language.

Scratch 2.0 features

[edit]

Scratch 2.0 does not treat procedures as first class structures and has limited file I/O options with Scratch 2.0 Extension Protocol, an experimental extension feature that allows interaction between Scratch 2.0 and other programs.[79] The Extension protocol allows interfacing with hardware boards such as Lego Mindstorms[80] or Arduino.[81] Scratch 2.0 also has the following features:

  • Smart block switching
  • Two-column category menu
  • Reverse order of project controls
  • Display stage on left side
  • Square block inputs
  • Compact editor
  • Collapsing sprite properties
  • Scratch 2.0 themes

Snap! (Build Your Own Blocks)

[edit]

A more advanced visual programming language inspired by Scratch is Snap!, featuring first class procedures (their mathematical foundations are also called lambda calculus), first-class lists (including lists of lists), and first-class truly object-oriented sprites with prototyping inheritance, and nestable sprites, which are not part of Scratch.[82] Snap! (previously "BYOB") was developed by Jens Mönig[83][84] with documentation provided by Brian Harvey[85][86] from University of California, Berkeley and has been used to teach "The Beauty and Joy of Computing" introductory course in CS for non-CS-major students.[87] Both of them were members of the Scratch Team before designing "Snap!".[88][22]

ScratchJr

[edit]

In July 2014, ScratchJr was released for iPad, and in 2016, ScratchJr for Android. Although heavily inspired by Scratch and co-led by Mitch Resnick, it is nonetheless a complete rewrite designed for younger children—targeting ages 5 through 7.[89]

Community-made modifications

[edit]

Due to the open source nature of Scratch, numerous forks and browser extensions have been created by the community that aim to improve or modify the user experience. ScratchTools and Scratch Addons are some examples of open-sourced browser extensions that add many upgrades and new features to the Scratch website and editor.[90][91]

TurboWarp is a fork of the Scratch 3.0 editor that compiles Scratch into JavaScript code when a project is run, resulting in projects' general performances boosting significantly.[92] In addition, there are many technical settings and the same addons that Scratch Addons provides.[93] TurboWarp can also export projects to standalone HTML5, Bundle (macOS) and EXE files.[94]

Users can also create their own extensions for Scratch 3.0 using JavaScript.[95] Although the intention for Scratch 3.0 was to allow unofficial JavaScript extensions to be developed by users, it was abandoned due to moderation risks. As a result, the official site doesn't allow JavaScript extensions to be added, but several modifications of Scratch do.

Before 2.0, a number of Scratch forks[96][better source needed] were created using the source code of Scratch 1.4. These programs usually only included a few extra blocks not present in Scratch.[97][better source needed]

See also

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Scratch (programming language)

View on Grokipedia
from Grokipedia

Scratch is a free, block-based and platform designed to enable children to create interactive stories, games, animations, and other while introducing core and problem-solving concepts. Developed initially by the Lifelong Kindergarten group at the Massachusetts Institute of Technology's Media Lab, it targets learners primarily aged 8 to 16 but appeals broadly to beginners in programming. Launched publicly in May 2007, Scratch features a drag-and-drop interface that assembles code blocks to avoid syntax errors, promoting and iteration. The platform fosters a global community where users share, , and collaborate on projects, with over 135 million registered accounts and more than 164 million shared creations recorded as of mid-2024, reflecting its widespread adoption in education and . Available in over 70 languages and moderated by the nonprofit Scratch Foundation since its transition from direct MIT oversight, Scratch emphasizes equity, self-expression, and creative computation over rote coding drills. Empirical studies demonstrate its efficacy in enhancing student engagement, emotional investment in learning, and performance in programming fundamentals, particularly through hands-on project-based activities that build sequential reasoning, event handling, and variable manipulation skills. While celebrated for lowering and sparking interest in among youth—evidenced by its role in millions of annual new users and integration into curricula worldwide—Scratch has drawn critique from some computing educators who contend its abstracted visuals may insufficiently convey the logical rigor and demands of text-based languages, potentially hindering transitions to professional programming tools.

History and Development

Origins at MIT Media Lab

The development of Scratch originated within the Lifelong Kindergarten research group at the , led by , with initial work commencing in 2002. The project drew inspiration from observations of children in after-school programs like the Computer Clubhouse network, where participants struggled with text-based programming languages but showed enthusiasm for creative expression through computers. Resnick's group sought to create a visual programming environment that embodied constructionist principles, influenced by Seymour Papert's language, emphasizing low-floor, high-ceiling, and wide-wallwidth accessibility for learners aged 8 to 16. A key spark for the name "Scratch" came from group member Oren Zuckerman in 2002, evoking the improvisational remixing style of DJs scratching records to parallel the intended playful, iterative coding process. The first prototype emerged around late 2002 to early 2003, with a more defined version dated October 11, 2003, featuring block-based scripting to avoid syntax errors common in traditional coding. Development received support from a grant spanning 2003 to 2007, enabling a team including technical lead John Maloney to refine the interface for intuitive drag-and-drop assembly of code blocks representing commands for sprites and . This foundational phase at the Media Lab prioritized empirical testing with youth users, iterating based on playtesting feedback to ensure the tool fostered without requiring prior expertise, setting the stage for its public release in 2007. The effort reflected the Lab's broader mission to integrate technology with creative learning, building on prior projects like to promote lifelong kindergarten-style .

Early Versions and Iterations

The initial public release of Scratch occurred on May 15, 2007, as a downloadable desktop application developed by the MIT Media Lab's Lifelong Kindergarten Group. This version introduced a block-based programming interface allowing users to create interactive media projects using sprites, backdrops, and scripts assembled via drag-and-drop, with support for multimedia elements like sound and . The accompanying website launched on the same date, enabling project sharing, though early adoption focused on offline use in educational settings. Subsequent iterations refined Scratch 1.x through incremental updates addressing usability, stability, and functionality. Scratch 1.1, released on May 26, 2007, primarily updated the Control blocks category to improve sequencing and looping capabilities. Version 1.2 followed on December 2, 2007, incorporating additional blocks for enhanced motion and sensing, alongside bug fixes and performance optimizations. Further advancements came with Scratch 1.3 on September 2, 2008, which added support for lists to enable data storage and manipulation in scripts. The final iteration, Scratch 1.4, released July 2, 2009, featured a revamped for better sprite editing and cloning, new sensing blocks for variable detection, and improved compatibility with international keyboards, marking the culmination of desktop-focused enhancements before the shift to web-based development. These updates collectively expanded Scratch's expressiveness while maintaining its core accessibility for young learners, with over 1 million projects shared by 2010.

Establishment of Scratch Foundation

The Scratch Foundation was founded in 2013 as the Code-to-Learn Foundation by , a professor of learning research at the MIT Media Lab's Lifelong Kindergarten Group, and David Siegel, co-founder and co-chairman of the investment firm . The organization was established as an independent nonprofit to address the need for sustainable funding and broader dissemination of Scratch, which had been developed at MIT since its initial release in 2007 but faced limitations in scaling under university auspices alone. It achieved 501(c)(3) tax-exempt status in 2014, enabling it to focus on to support Scratch's ecosystem, including online community resources, educational events, and global outreach. In July 2015, the foundation renamed itself the Scratch Foundation to more directly align with its core mission of promoting Scratch as a tool for among youth, emphasizing engagement in systematic reasoning, collaboration, and self-expression through programming. This rebranding reflected Scratch's growing prominence following the 2013 release of Scratch 2.0, which shifted the platform to a web-based model and spurred rapid user expansion. The foundation's establishment marked a transition for Scratch from primarily MIT-led development to a model involving external partnerships, with the nonprofit assuming responsibilities for moderation, resource creation, and long-term sustainability to reach underserved communities worldwide. By 2019, plans were announced to further empower the foundation to lead in Scratch's , updates, and support infrastructure.

Core Design and Features

Block-Based Programming Paradigm

Scratch employs a block-based visual , where users construct programs by dragging and snapping together graphical blocks that represent code elements, rather than typing text commands. These blocks, resembling interlocking puzzle pieces, are organized into color-coded categories such as Motion for sprite movement, Control for loops and conditionals, and Sensing for detecting user inputs or environmental states, enabling users to build scripts intuitively without manual syntax management. This approach inherently prevents syntax errors by ensuring blocks only connect in valid sequences; for instance, a "move 10 steps" block from the Motion category can attach below an event-triggering "when clicked" hat block, but incompatible shapes reject invalid attachments. Developed by researchers at the , the paradigm draws from earlier educational tools like but emphasizes immediate visual feedback and event-driven execution to foster creativity and in learners aged 8 to 16, as outlined in foundational documentation on Scratch's design. Block types include hat blocks to initiate scripts on events, stack blocks for linear command sequences, reporter blocks that output numerical or string values for use in other blocks, blocks yielding true/false conditions, and cap blocks to conclude loops or sequences without further attachments. Core Scratch provides over 100 such blocks, extensible via plugins, allowing construction of complex behaviors like conditional branching or variable manipulation while maintaining accessibility for beginners. The paradigm's efficacy stems from its reduction of —studies on visual languages note decreased error rates compared to text-based coding, though it limits advanced refactoring common in professional environments.

User Interface and Workflow

The Scratch user interface features a central that serves as the runtime environment for displaying backdrops and sprite interactions during project execution. Adjacent to the stage, the sprites pane lists thumbnails of all sprites and the stage itself, enabling users to select elements for by clicking on them. Below the stage, the scripts area provides space for assembling blocks specific to the selected sprite or stage. On the left side, the block palette organizes draggable code blocks into color-coded categories, including Motion (blue) for positional changes, Looks (purple) for , Sound (pink) for audio, Events (yellow) for triggers, Control (orange) for flow structures like loops and conditionals, Sensing (light blue) for inputs, Operators () for calculations, and Variables () for . Additional categories such as Pen for and My Blocks for custom procedures appear as needed. Users access the editor by logging into the Scratch website at scratch.mit.edu and selecting "Create" to open a new project, which initializes with a default cat sprite and blank . To build functionality, users add sprites via the sprites pane options: choosing from the built-in , drawing in the paint editor, uploading images, or using surprises for random assets. With a sprite selected, compatible blocks are dragged from the palette and snapped together in the scripts area to form sequential stacks, where shape and notch designs prevent invalid connections and promote logical assembly. Scripts typically begin with event blocks like "when clicked" to initiate execution upon user activation. Project execution follows by clicking the icon above , which runs all eligible scripts in parallel, updating in real-time to reflect sprite movements, changes, and interactions. Users halt execution via the red stop sign, allowing iterative testing and by modifying blocks—such as dragging them apart or back to the palette—and re-running. Completed projects can be saved automatically to the user's online account, shared publicly for viewing and remixing, or exported as .sb3 files for offline use, supporting collaborative workflows where remixes build upon originals with attribution. This drag-and-drop paradigm minimizes syntax errors, enabling focus on computational concepts like sequencing, looping, and conditionals through visual feedback.

Extensions and Customization

Scratch extensions provide modular additions to the core programming environment, introducing new block categories for specialized functionalities such as hardware integration and advanced . Users activate extensions by selecting them from the Extensions menu in the bottom-left of the editor interface, which dynamically loads corresponding blocks into the palette without altering the base system. This design, implemented in Scratch 3.0, separates optional features from essential ones to streamline the initial while enabling expansion. The platform includes eleven official extensions as of Scratch 3.0's release on January 2, 2019: five software-focused ones—Music (for synthesis and ), (for vector drawing and stamping), Video Sensing (for camera-based motion detection), Text to Speech (for converting text to synthesized audio), and Translate (for real-time language conversion using )—and six hardware-oriented ones supporting devices like (for motor and sensor control), (for pins and accelerometer data), LEGO WeDo 2.0 (for tilt and distance sensing), LEGO BOOST (for color and force feedback), and Vernier Go Direct sensors (for force and acceleration measurements). These extensions facilitate interdisciplinary applications, such as and projects, by bridging visual programming with . Beyond extensions, customization occurs through user-defined procedures, termed "My Blocks" or custom blocks, which encapsulate reusable code sequences within a sprite or the stage. Created via the "Make a Block" button in the My Blocks palette, these allow definition of hat blocks with optional input parameters, run-with-without-screen-refresh modifiers for performance, and recursion capabilities. For instance, a custom block might abstract a movement routine with speed and direction inputs, promoting code modularity and reducing redundancy across scripts. This feature supports abstraction principles fundamental to programming, enabling beginners to build complex behaviors from simpler, parameterized components. While official extensions are sandboxed for security and compatibility, community efforts like Scratch Addons—a browser extension—offer unofficial customizations such as enhanced themes, debugging tools, and additional blocks via JavaScript modifications, though these operate outside the core Scratch runtime and require third-party environments like TurboWarp for full extension support. TurboWarp is an open-source online modification of Scratch, started around 2020 by members of the Scratch community, that enhances performance by compiling projects to JavaScript for faster execution. It includes features such as dark mode, addons for improved editor functionality, and support for community-created extensions beyond official limitations. Hosted on GitHub under the TurboWarp organization, it addresses some of Scratch's performance issues while expanding creative options, though users should be aware of potential compatibility risks as it operates outside official support.

Versions and Evolution

Scratch 1.0 and 2.0

Scratch 1.0, the first stable public version of the Scratch programming language, was released on May 15, 2007, by researchers at the MIT Media Lab's Lifelong Kindergarten Group. Designed as a desktop application for Windows, macOS, and , it required no connection for core functionality and emphasized visual block-based programming to lower barriers for young users aged 8 and older. The interface featured a central for project playback, a sprites pane for character management, and categorized blocks for motion (e.g., "move 10 steps"), appearance changes, sound playback, (e.g., loops and conditionals), sensing inputs like mouse position, mathematical operators, and user-defined variables. Projects were saved as .sb files, supporting basic sprite importation from image formats and limited scripting without advanced features like dynamic object creation or modular procedures. Minor iterations followed, including Scratch 1.4 released in late 2011, which introduced compatibility with more image and sound file types (e.g., vectors partially, audio), webcam integration for sprite capture, and bug fixes for stability, while retaining the offline-only model and core block set. These updates addressed usability issues reported by educators but did not alter the fundamental desktop-bound , limiting seamless online collaboration. Scratch 2.0 launched on May 9, 2013, marking a shift to browser-based editing via , alongside a compatible offline desktop editor, to enable direct project sharing and remixing without file downloads. This version expanded programming capabilities with new blocks for sprite cloning (e.g., "create clone of myself" and "when I start as a clone"), custom blocks for reusable procedures with parameters, and enhanced handling for . The was streamlined with resizable panes, editing tools for scalable sprites, improved costume and backdrop libraries, and better support including instruments. with 1.x projects was maintained through conversion tools, though some advanced 2.0 features required adaptation, facilitating broader community engagement while preserving core accessibility.

Scratch 3.0 Release and Updates

Scratch 3.0 was released on January 2, 2019, marking a complete redesign and reimplementation of the platform by the MIT Media Lab. This version transitioned from Adobe Flash to HTML5, enabling compatibility with tablets, smartphones, and modern browsers without plugin dependencies. The update introduced a responsive interface optimized for touchscreens, facilitating project creation on mobile devices. Key enhancements in Scratch 3.0 included dozens of new sprites and backdrops, a redesigned vector-based paint editor with an tool, and an upgraded sound editor supporting visualization and effects. New programming blocks expanded capabilities for video sensing, , and custom procedures, while the "My Blocks" category allowed users to define and manage custom blocks more effectively. Extensions were added for integrating hardware like , music instruments, and text-to-speech, with cloud-hosted options such as for multilingual support. Post-release updates to Scratch 3.0 have focused on stability, accessibility, and feature refinements. The offline editor reached version 3.29.1 by February 2022, incorporating bug fixes and performance improvements. The Scratch team publishes a public detailing ongoing changes, including UI tweaks, security enhancements, and compatibility updates as recent as August 2025. These iterative releases ensure the platform remains current without a full major version shift, with no Scratch 4.0 launched by October 2025.

ScratchJr and Variants

ScratchJr is a visual, block-based programming application targeted at children aged 5 to 7, enabling them to construct interactive stories and games through simplified coding that emphasizes sequencing, repetition, and basic event handling to foster early and problem-solving skills. Unlike the full Scratch platform, it employs larger, touch-optimized blocks categorized into motion (e.g., move forward, turn), appearance (e.g., grow, change color), sounds, and basic control structures like "repeat" for loops and trigger events such as "when started" or "when tapped," deliberately omitting advanced elements like variables, custom functions, or complex conditionals to match young users' . The interface features a for placing sprites and backgrounds, with intuitive drag-and-drop mechanics designed for tablet use, promoting creativity without requiring text-based input or keyboard navigation. Developed primarily by the DevTech Research Group at under Marina Umaschi Bers, in partnership with researchers including , ScratchJr drew inspiration from Scratch's core principles but adapted them for and early elementary learners through iterative prototyping focused on empirical testing with children. The project prioritized accessibility, with free availability and no login requirements, aiming to democratize introductory programming amid evidence from studies showing benefits in spatial reasoning and skills. The version launched as a free app in July 2014, requiring iOS 9.3 or later, while the Android tablet edition followed in 2016; by May 2025, the app had amassed over 60 million downloads worldwide, reflecting widespread adoption in informal and settings. ScratchJr supports multilingual interfaces in over 40 languages, facilitating global adaptations for diverse educational contexts, though core functionality remains consistent across versions without platform-specific overhauls. No official desktop or web-native variants exist from the developers, preserving the tablet-centric model to leverage touch interaction for development; however, third-party web emulations have emerged to extend access on browsers, albeit lacking official endorsement and potentially diverging in fidelity to the original design. Educational extensions include multi-device curricula for collaborative projects, where multiple tablets synchronize to create shared games or narratives, but these represent usage modes rather than distinct software variants. Updates have focused on bug fixes and minor UI refinements rather than major feature additions, maintaining stability for its young audience.

Planned Scratch 4.0 Developments

The Scratch Foundation designated the development of Scratch 4.0 as one of three strategic priorities for 2025, emphasizing enhancements to support the platform's expanding user base of over 100 million active accounts. This iteration aims to incorporate a re-imagined alongside creative AI functionalities, as outlined in foundation job postings and planning documents from late 2024 onward. These updates seek to address challenges and evolve the platform's collaborative features while maintaining its core block-based paradigm for novice programmers. A prominent planned feature is the Creative Learning Assistant (CLA), an opt-in AI tool announced on July 22, 2025, intended to serve as a customizable co-pilot for young users. The CLA will provide personalized guidance, inspiration prompts, and project suggestions tailored to individual , enabling children to assistants that reflect their preferences and creative processes. Demonstrated at the Scratch Conference 2025, it focuses on fostering independent problem-solving rather than automating code generation, with safeguards to ensure age-appropriate interactions and data privacy. Funding for Scratch 4.0 forms part of a $30 million initiative launched in to drive platform evolution, youth engagement programs, and long-term sustainability. No official release timeline has been confirmed, though informal statements from foundation representatives indicate a target for the second half of 2026, following iterative testing similar to prior versions. Development draws from user feedback and research into AI's role in , prioritizing ethical integration to avoid over-reliance on automation.

Technical Implementation

Underlying Code Base

Scratch 1.x implementations relied on , an open-source Smalltalk system, which provided the runtime environment for executing block-based scripts through a custom tailored for educational programming. This foundation emphasized object-oriented principles, with sprites and stage elements modeled as Smalltalk objects to simulate parallelism via green threads. Scratch 2.0 transitioned to () for the editor and player, enabling richer multimedia support and offline standalone applications while maintaining compatibility with web browsers via plugins. The codebase included a Flash-based renderer for , , and user interactions, with project files serialized in a format that compiled blocks into bytecode for execution. Scratch 3.0, introduced in January 2019, adopted modern web standards with , CSS, and as its core technologies, facilitating browser-native operation without plugins and supporting mobile devices. The editor's frontend utilizes React for component-based UI management, while the block system integrates —a library co-developed with —to parse visual blocks into executable code. Runtime execution occurs via a virtual machine that handles concurrency through cloned sprite instances and event-driven dispatching, rendering with Canvas and Web Audio API for . The open-source codebase resides in the Scratch Foundation's repositories, including scratch-www for the web editor and scratch-vm for the core engine, enabling extensions and third-party modifications.

File Formats and Compatibility

Scratch projects are stored in version-specific formats: Scratch 1.x uses .sb files, which employ a binary structure not easily extractable without specialized tools. Scratch 2.0 introduced .sb2 files, ZIP archives containing a project.json file with serialized blocks and metadata, alongside embedded assets like sprites and sounds in directories such as sprites/ and sounds/. Scratch 3.0 adopted .sb3 files, also ZIP-based but with an updated project.json schema supporting new features like enhancements and extensions, while maintaining backward-compatible elements for core scripts. These formats ensure self-contained projects with serialized code in for blocks, allowing offline editing and sharing, though .sb files predate the ZIP standard used in later versions. Assets within projects support specific imports: images in , , JPG, GIF, and BMP; sounds primarily in and , with potential compatibility limits for uncompressed or proprietary audio. Compatibility prioritizes playback over full editing across versions. Projects from Scratch 1.x or 2.0 can be uploaded to the Scratch 3.0 online platform and executed, as the system renders older blocks via emulation layers. However, loading them into the Scratch 3.0 editor for modification may fail or degrade features, such as unsupported clones, custom blocks, or asset types, due to schema changes and removed legacy elements like certain pen extensions. Upgrading is straightforward: opening an .sb or .sb2 file in Scratch 3.0 prompts automatic conversion to .sb3 upon saving, preserving core logic while adapting incompatible blocks—though users must manually recreate or approximate lost functionalities. Downgrading .sb3 to .sb2 lacks native support and often requires unzipping, editing manually, and repackaging, risking from 3.0-exclusive features like costume vectors or cloud variables. Very early prototypes in .scratch format remain incompatible without custom extraction. The Scratch Team emphasizes maximal to sustain long-term project viability, but version transitions necessitate testing for edge cases.

Online vs. Offline Functionality

The online editor of Scratch, accessible via web browsers at the official MIT-hosted , requires an active connection to load the interface, access media libraries, and persistently save projects to user accounts. This setup facilitates seamless integration with the platform's community ecosystem, including public sharing, remixing of others' projects, real-time indicators, and features like variables that synchronize data across multiple sessions or devices. Without , the online editor becomes inoperable for editing or saving, though cached elements may allow limited viewing of previously loaded projects in some browsers. The offline counterpart, known as the Scratch Desktop application (or Scratch app), is a downloadable standalone program available from the official site for and later, macOS 10.13 and later, and select mobile platforms via app stores. Launched alongside Scratch 3.0 in 2019, it enables full project creation, editing, and local storage without any internet dependency, using the same block-based interface and core programming features as the online version. Projects are saved as .sb3 files on the user's device, which can later be uploaded to the online platform when connectivity is restored, ensuring compatibility for transfer. Functionally, the offline editor replicates the visual programming environment, including sprite manipulation, scripting, and extensions like or video sensing, but omits online-exclusive elements such as direct interaction, automatic backups to MIT servers, and cloud variables. Users report smoother performance in the offline mode due to native application rendering avoiding browser overhead, reduced latency in block dragging, and enhanced since no data transmits to external servers during creation. This makes it particularly suitable for environments with intermittent or no , such as remote classrooms or personal devices in low-connectivity areas, though it necessitates manual file management for sharing. No official support exists for distributions, leading users to rely on unofficial ports or emulators.

Community and Usage

User Demographics and Growth Statistics

Scratch has experienced substantial growth since its public launch in 2007, accumulating over 164 million shared projects and reaching 135 million registered users by September 2025. This marks an increase from 100 million users in December 2022, reflecting accelerated adoption amid global educational expansions. The platform reports approximately 1.4 million active project creators and 625,000 active commenters monthly as of late 2024, indicating sustained engagement beyond registration. User demographics skew toward children and early adolescents, with the highest concentrations among 10- to 13-year-olds; for example, registered users include about 9 million 12-year-olds, 8.6 million 11-year-olds, 7.7 million 13-year-olds, and 6.8 million 10-year-olds. The average user age hovers around 12 years, and roughly 75% of projects originate from those under 16. Gender distribution shows near parity, with approximately 45% of users identifying as , a higher proportion than in many text-based programming communities. Geographically, Scratch users span over 150 countries and more than 70 languages, with notable growth in regions like , where new registrations doubled from 2020 to 2021. The platform collects basic demographic data including country upon signup, enabling worldwide distribution tracking, though precise country breakdowns vary by activity levels rather than registration alone.

Online Community Dynamics

The Scratch online community centers on user-generated content sharing, where registered members upload interactive projects for public viewing, remixing, and collaboration. Remixing, a foundational feature since the platform's 2007 launch, enables users to fork and modify existing projects, fostering iterative creativity and knowledge transfer among participants, particularly youth learning programming concepts. This mechanic has driven extensive project evolution, with studies of longitudinal data from 2008 to 2012 revealing patterns of participation where novice users often remix popular works to gain skills before creating originals. By design, remixes do not automatically notify originators, which supports open experimentation but can lead to uncredited adaptations, shaping community norms around attribution via project credits or descriptions. Community engagement metrics underscore rapid growth and interaction density. As of October 2023, the platform hosted over 135 million registered users who had shared more than 164 million projects, posted nearly 990 million comments, and formed over 34 million studios—curated collections for collaborative themes. In alone, project creations surged 39% year-over-year to exceed 113 million, reflecting heightened participation amid global remote learning shifts. Collaborative practices, such as "collabs" organized via forums or studios in response to challenges, enable voluntary on shared or animations, with identifying these as key to sustained involvement among diverse demographics. Such dynamics promote civic elements, including themed sharing around social issues, though primarily within creative constraints. Moderation challenges persist due to the platform's scale and youth-oriented user base, relying on automated filters, user reports, and a limited moderator team to address spam, harassment, and inappropriate content. Common violations include spam comments flooding high-visibility projects and occasional explicit imagery slipping into explore sections, as reported in user forums and external discussions. Enforcement through reports can appear inconsistent, with valid content sometimes removed due to mass flagging by coordinated groups, while persistent spammers exploit visibility for disruption. Prior experiments with community moderators were discontinued after instances of misuse, leaving centralized oversight strained by volume, which impacts perceived fairness and user retention. Despite these issues, the absence of algorithmic amplification reduces echo chambers compared to broader social media, prioritizing creative exchange over virality.

Educational Integration and Events

Scratch has been integrated into educational settings worldwide, particularly in primary and secondary schools, to introduce students to programming concepts through visual block-based coding. Studies indicate its use enhances and engagement, with applications in science lessons via models like the 5E instructional framework, where Scratch activities improved student outcomes in understanding concepts such as energy transfer. In elementary education, it supports interactive learning of , with evidence from classroom implementations showing increased cognitive, emotional, and behavioral engagement, raising average scores from 3.3 to 4.0 for first graders. Educators employ Scratch across subjects including , , and ICT, often in one-hour workshops or ongoing clubs to meet standards for computational skills. The MIT Scratch Team and collaborators provide dedicated resources for educators, including the Creative Computing curriculum developed by the Harvard Graduate School of Education's ScratchEd team, which offers lesson plans, activities, and assessment tools for classroom implementation. ScratchEd, launched in July 2009, serves as an online community for over a , enabling teachers to share projects, tutorials, and discussions on pedagogical strategies. These materials emphasize , where students create games and stories to build problem-solving abilities, with guides tailored for diverse age groups from ages 8 to 16. Annual events foster educational adoption through global gatherings. Scratch Days, organized as a network of local events, encourage sharing of projects and experiences; in 2024, peer organizations hosted over 800 such events across 30 countries, engaging more than 100,000 participants. The MIT Scratch Conference, held periodically, convenes educators, researchers, and developers for workshops and discussions; the 2021 virtual edition focused on playful learning amid remote education shifts, while the 2025 conference is scheduled to continue this tradition. Scratch Week, an extension of Scratch Day, ran virtually from May 17 to 23 in recent years, promoting creation and sharing without geographic limits. These events, supported by the Scratch Foundation, provide hands-on professional development, with sessions on integrating Scratch into curricula during the school closures, when adoption surged.

Impact and Reception

Achievements in User Engagement

Scratch has demonstrated substantial user engagement through its expansive , with over 135 million registered users as of mid-2024. This milestone builds on the platform reaching 100 million users worldwide in December 2022, establishing it as one of the largest free coding communities for young people. The growth reflects sustained participation, evidenced by more than 164 million projects shared publicly, enabling users to create, remix, and iterate on interactive stories, games, and animations. Interaction metrics further highlight engagement depth, including nearly 990 million comments posted, which facilitate feedback, , and discussion among users. Over 34 million studios—curated collections for group projects—have been created, supporting organized community efforts and thematic explorations. Annual project creation peaked at 1.47 million in March 2024, a near 50% increase from comparable periods the prior year, indicating robust ongoing activity. User surveys underscore the platform's appeal, with 87% of participants reporting joy during use and citing motivations like and belonging. These outcomes stem from design features promoting low-barrier entry and social sharing, fostering repeated logins and contributions without formal incentives. Global participation spans diverse demographics, with projects and comments reflecting multilingual and cross-cultural exchanges, though varies by age and experience level.

Evidence on Skill Transfer to Text-Based Coding

Research on the transfer of skills from Scratch's block-based programming to text-based languages like Python reveals challenges in direct translation, with empirical evidence indicating that unmediated transitions often result in persistent misconceptions about core concepts such as variables, sequencing, selection, and loops. A quasi-experimental study involving 163 sixth-grade students found that students transitioning from block-based environments (using MakeCode for ) to Python without structured bridging exhibited higher rates of these misconceptions compared to those receiving direct text-based instruction; however, a mediated bridging approach—explicitly mapping block constructs to textual equivalents—significantly reduced misconception prevalence in the experimental group across all tested areas. This suggests that while Scratch fosters initial , syntactic and structural differences hinder seamless transfer absent pedagogical interventions. Dual-modality environments, which allow simultaneous visualization of block and text representations, demonstrate superior outcomes for acquisition during transition compared to one-way tools like read-only . In an experimental comparison with 10 participants solving Python tasks, all reported that dual-modality tools (e.g., BlockPy) facilitated easier understanding and problem-solving, with statistically significant advantages in perceived easiness (p=0.00024), though no differences emerged in satisfaction or enjoyment. Such tools mitigate the of syntax learning by leveraging visual familiarity from Scratch, enabling learners to focus on algorithmic logic. High school quasi-experimental studies further corroborate partial transfer, where prior block-based experience yielded comparable post-assessment scores to text-first groups but required explicit instruction to equate performance in and tasks. Longitudinal and broader meta-analytic evidence remains limited, with case studies highlighting difficulties: in a Colombian sample of programmers, most successfully transferred concepts between block-based languages but struggled to articulate or implement equivalent text-based programs, attributing failures to overlooked and error-handling nuances. Meta-analyses comparing block- and text-based environments for novices report block-based tools enhancing initial cognitive outcomes like sequencing and conditionals, but they do not robustly address post-block transfer, underscoring a gap in causal evidence for sustained proficiency in professional languages. Overall, while Scratch builds foundational problem-solving applicable to text coding, empirical data emphasize the necessity of targeted bridging strategies to realize transfer, as unsupported shifts risk reinforcing incomplete mental models rather than accelerating expertise.

Criticisms and Controversies

Debates on Pedagogical Effectiveness

Proponents of Scratch argue that it effectively cultivates (CT) skills such as , , and among young learners, supported by empirical studies demonstrating measurable improvements. A of K-9 found that Scratch-based interventions consistently enhanced CT competencies, with participants showing gains in logical sequencing and problem-solving through visual block manipulation. Similarly, a 2022 study on Chinese students reported significant CT skill elevation post-Scratch exposure, attributing this to its intuitive interface that reduces on syntax. These findings align with broader evidence from interventions, where ScratchJr variants yielded positive effects on coding proficiency and reflective thinking, though effects on broader CT were moderate. Critics contend that Scratch's block-based paradigm oversimplifies programming fundamentals, failing to instill essential practices like , , and error handling that are core to text-based languages. Educators have highlighted the absence of built-in tools, which leaves users without exposure to real-world , potentially fostering misconceptions about code execution. Comparative analyses reveal that while Scratch boosts initial engagement and basic CT, it underperforms relative to text-based Python in advancing deeper CT skills, such as , with secondary students exhibiting superior attitudes and behaviors in text environments. A 2024 study comparing block- versus text-based programming confirmed that text-based approaches better support transferable skills, as block systems limit abstraction levels and function returns. The debate centers on skill transfer to professional coding: while Scratch excels in —evidenced by increased academic in introductory programming via gamified projects—empirical on long-term transfer remains inconclusive, with some reviews noting overreliance on visual aids may delay mastery of textual paradigms. Critics from practitioner communities argue it promotes "drag-and-drop" habits over rigorous logic, echoing concerns that educational tools like Scratch prioritize accessibility over depth, potentially requiring supplemental text-based training for true proficiency. Proponents counter that early CT gains via Scratch provide a causal foundation for later transitions, as seen in curricula bridging to languages like , though independent verification of sustained outcomes is sparse. Overall, while Scratch demonstrably aids novice engagement, its pedagogical ceiling invites scrutiny, with evidence favoring hybrid approaches for comprehensive skill development.

Community Moderation and Content Issues

Scratch's moderation system primarily relies on user-submitted reports via a dedicated "" button for projects, comments, profiles, or studios deemed disrespectful, violent, or otherwise guideline-violating, with the Scratch Team reviewing submissions reactively rather than through proactive scanning. This approach, intended for a platform serving users aged 8 and older, has drawn criticism for inconsistency, as harmless projects or comments are sometimes flagged or removed without clear justification, while rule-breaking content persists. Inappropriate content, including sexual imagery and borderline NSFW material, has repeatedly surfaced on the platform, with instances visible in high-traffic areas like the Explore section as recently as July 3, 2025, prompting parental alerts and concerns over child exposure. Users report violent, spammy, or disruptive projects evading detection until mass-flagged, exacerbating delays due to the Scratch Team's limited resources amid millions of monthly active users. Controversies include perceived overreach, such as bans on functional code snippets from other languages or historical simulations deemed "offensive," like a mod in March 2024, which critics argue stifles legitimate creativity under vague community guidelines. False or mass reporting is debated, with some users claiming wrongful bans and others asserting most complaints stem from actual violations, though the lack of transparency in review processes fuels distrust. Community discussions highlight the need for expanded tools, like AI-assisted flagging or larger teams, to address overwork without relying solely on reports. Earlier analyses praised Scratch's for fostering civil dialogue through norms, but recent user feedback indicates declining effectiveness, with calls for evidence-based decisions and graduated responses short of outright bans. Despite these issues, the platform maintains no widespread evidence of in preventing egregious harm, though parental and reporting are recommended for safe use in educational settings.

Limitations in Scope and Real-World Applicability

Scratch, as a block-based visual programming environment, is inherently constrained to simpler constructs suitable for learners, lacking native support for advanced structures such as arrays or efficient parameter passing between objects, which renders it cumbersome for projects exceeding basic games or animations. These architectural choices prioritize over , resulting in performance degradation for larger-scale endeavors; for instance, projects are capped by a 5MB limit on the underlying file size, beyond which functionality becomes unreliable. Empirical analyses of Scratch usage confirm its unsuitability for complex coding tasks, with studies identifying it as inadequate for developing substantial applications or addressing intricate computational problems due to absent features like modular and optimized execution. In terms of real-world applicability, Scratch finds negligible adoption in professional software development, where text-based languages dominate for their precision, version control integration, and deployability across diverse hardware ecosystems. Its visual paradigm, while fostering initial computational thinking, does not equip users with the syntactic rigor or debugging tools essential for industry-standard workflows, as evidenced by the absence of Scratch in commercial project repositories or enterprise tools. Transitioning to professional programming often requires unlearning Scratch-specific habits, such as reliance on drag-and-drop blocks, which hinder familiarity with textual code editing and command-line interfaces prevalent in real-world engineering. Furthermore, Scratch's sandboxed execution model restricts integration with external APIs, databases, or hardware beyond basic extensions, limiting its utility to educational prototypes rather than production-grade systems. Critics note that while Scratch excels in motivational engagement for children aged 8-16, its scope excludes domains like , , or web backend development, where imperative control and performance optimization are paramount. Longitudinal evidence on skill transfer remains mixed, with some preservice educators reporting improved attitudes toward programming but no direct pathway to professional proficiency without supplementary text-based training. This positions Scratch as a gateway tool rather than a comprehensive platform, effective for conceptual foundations yet insufficient for bridging to vocational coding demands.

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